U.S. patent application number 11/359242 was filed with the patent office on 2006-08-31 for device and process for manufacturing undulating plies.
This patent application is currently assigned to Michelin Recherche et Technique S.A.. Invention is credited to Michel Filhon, Bernard Jault.
Application Number | 20060191618 11/359242 |
Document ID | / |
Family ID | 35124509 |
Filed Date | 2006-08-31 |
United States Patent
Application |
20060191618 |
Kind Code |
A1 |
Jault; Bernard ; et
al. |
August 31, 2006 |
Device and process for manufacturing undulating plies
Abstract
Process and device intended for the production of an undulating
ply (O) formed of a ply of rubber mix reinforced by reinforcement
cords (R) arranged side by side in the longitudinal machine
direction at a given pitch, in which ply the reinforcement cords
(R) form, in the plane of the ply, undulations in the transverse
direction of a controlled amplitude and period. This device
comprises means for delivering, a continuous straight-cord ply (D),
means (1) for undulating the reinforcement cords in the plane of
the ply, means (2) for applying retaining cords (B) in the
longitudinal direction of the ply.
Inventors: |
Jault; Bernard; (Aulnat,
FR) ; Filhon; Michel; (Clermont-Ferrand, FR) |
Correspondence
Address: |
COHEN, PONTANI, LIEBERMAN & PAVANE
551 FIFTH AVENUE
SUITE 1210
NEW YORK
NY
10176
US
|
Assignee: |
Michelin Recherche et Technique
S.A.
Granges-Paccot
CH
|
Family ID: |
35124509 |
Appl. No.: |
11/359242 |
Filed: |
February 22, 2006 |
Current U.S.
Class: |
152/526 ;
152/531; 156/199; 156/459 |
Current CPC
Class: |
B29C 70/504 20130101;
Y10T 156/1007 20150115; B29D 30/38 20130101; Y10T 152/10765
20150115; B29D 30/70 20130101; B29D 2030/381 20130101 |
Class at
Publication: |
152/526 ;
156/199; 156/459; 152/531 |
International
Class: |
B60C 9/18 20060101
B60C009/18; B32B 37/00 20060101 B32B037/00 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 28, 2005 |
FR |
05/01995 |
Claims
1. A process for manufacturing a tire comprising an undulating ply
(O) consisting of a ply of rubber mix reinforced by reinforcement
cords (R) arranged side by side in the longitudinal machine
direction (L) at a given pitch (p1), and in which the reinforcement
cords (R) form, in the plane of the ply, undulations in the
transverse direction of an amplitude (A) and a period (P), which
process is characterised in that it comprises the following steps:
producing a continuous strip of continuous straight-cord ply (D)
composed of a ply of rubber mix reinforced by reinforcement cords
(R) arranged side by side and parallel to one another in the
longitudinal direction (L) at a given pitch (p1), using a
traditional process, displacing alternatively the whole of said ply
to create, transversely to the direction of the ply, undulations of
the reinforcement cords in the plane of the ply, depositing on at
least one of the faces of the undulating ply (O), in the
longitudinal direction, rectilinear retaining cords (B) by
arranging them transversely at a given pitch (p2).
2. A device intended for the production of an undulating ply (O)
formed of a ply of rubber mix reinforced by reinforcement cords (R)
arranged side by side in the longitudinal machine direction (L) at
a given pitch (p1), in which ply the reinforcement cords (R) form,
in the plane of the ply, undulations in the transverse direction of
a controlled amplitude (A) and period (P), which device is
characterised in that it comprises: means for delivering a
continuous straight-cord ply (D) composed of a ply of rubber mix
reinforced by reinforcement cords (R) arranged side by side and
parallel to one another in the longitudinal direction (L) at a
given pitch (p1), transverse displacement means for delivering an
undulated ply by displacing alternatively the whole of said ply, to
create transversely to the direction (L) of the ply, undulations of
the reinforcement cords in the plane of the ply, receiving means
(3) arranged downstream of the transverse displacement means (1)
and cooperating with the latter, means (2), arranged on the
downstream part of the receiving means (3), for applying retaining
cords (B) in the longitudinal direction (L).
3. A device according to claim 2, in which the means for
transversely displacing the straight-cord ply (D) comprise an
undulation roller (1) around which said straight-cord ply (D) is
wound, said undulation roller being moved at a circumferential
speed V1 and an alternating transverse movement of given period and
amplitude.
4. A device according to claim 2, in which the receiving means are
formed by a receiving roller (3) moved at a circumferential speed
V2 and around which the undulating ply (O) is wound.
5. A device according to claim 3, in which the distance (d) between
the circumference of the undulation roller (1) and the
circumference of the receiving roller (3) is adjustable.
6. A device according to claim 2, in which the surfaces of said
undulation (1) and receiving (3) rollers have properties which
enable them to increase the adherence of the plies (D, O)
travelling over their respective circumferences.
7. A device according to claim 6, in which the surfaces of the
undulation (1) and receiving (3) rollers have magnetic
properties.
8. A device according to claim 6, in which the surfaces of the
undulation (1) and receiving (3) rollers are thermally
controlled.
9. A device according to claim 2, in which the transverse
displacement means comprise a pair of gear-shaped roller in meshing
engagement to undulate the ply in a direction perpendicular to the
plane of the ply and rolls to lay down the undulated ply into a
planar arrangement.
10. A tire produced from an undulating ply (O), composed of a ply
of rubber mix reinforced by reinforcement cords (R) arranged side
by side in the longitudinal direction (L) at a given pitch (p1), in
which ply said reinforcement cords form, in the plane of the ply,
undulations in the transverse direction of a controlled amplitude
(A) and period (P), characterised in that rectilinear retaining
cords (B) are placed on at least one of the faces of the undulating
ply (O) in the longitudinal direction (L) and are arranged
transversely at a given pitch (p2) greater than the pitch (p1) of
the reinforcement cords (R).
11. A tire according to claim 10, in which the retaining cords (B)
of the undulating ply (O) are elastic and have a resistance to
elongation of approximately 5 daN at 5% elongation.
12. A tire according to claim 10, in which the retaining cords (B)
of the undulating ply (O) are slightly elastic and have a tensile
strength of between 2 daN and 10 daN.
13. A tire according to claim 10, in which the retaining cords (B)
of the undulating ply (O) are arranged transversely at a pitch (p2)
of between 10 and 50 mm.
Description
[0001] The invention relates to the field of manufacturing tires,
and in particular to the field of manufacturing semi-finished
products of the type of reinforcement plies used for example in the
crown belts of tires.
[0002] Crown belts usually comprise one or more reinforcement
belts, composed of cords coated in a rubber mix and forming given
angles generally of opposite signs relative to the circumferential
direction of the tire.
[0003] Furthermore, modern tires nowadays largely use what are
called zero-degree reinforcing threads, characterised by the fact
that they are formed of reinforcement cords forming a substantially
zero angle with the circumferential direction.
[0004] The processes for depositing these zero-degree reinforcing
threads are themselves widely known. They usually consist of
depositing on the shaped tire blank, [0005] either unit threads
coated with rubber product or strips of low width, formed of a
small number of unit threads, by winding successive turns over the
width of the crown, [0006] or one to two turns of a section of ply
made of semi-finished product itself formed of cords oriented at
zero degrees and the width of which corresponds substantially to
the width of the crown of the tire.
[0007] Here "strip" or "ply" is understood to mean a continuous
strip or a straight-cord ply made from a rubber mix and reinforced
by one or more cords arranged side by side, parallel to each other
and extending in the longitudinal direction of the strip. A "cord"
may refer to a unitary cord, a cabled yarn composed of several unit
threads, or alternatively a plied yarn, and it may be textile or
metallic in nature.
[0008] However, with the aim of solving the problems linked to the
variations in circumference of the tire blank between the step of
laying the zero-degree reinforcing threads and the final step of
shaping in a curing press, it was proposed to lay the cords or
strips of cords by forming slight undulations. This technique has
the advantage of being able to adapt the length of cords laid to
the final circumference of the tire.
[0009] In this respect, the technique of laying by winding turns of
cords or of strips of low width proves particularly suitable, in
particular for laying cords of low elasticity, such as metal wires,
for example. These techniques are described by way of illustration
in EP 1 208 963. They are characterised by laying the cord or strip
directly on the tire blank.
[0010] The process of producing continuous strips or plies
reinforced by cords which undulate in the plane of the ply, which
plies are commonly referred to by the name "undulating ply", is
distinguished from the above techniques in that this process
comprises two stages. In a first step, in a dedicated process,
undulating plies in the form of continuous strips of great lengths
are produced. Then in a second step the ply is cut into sections of
a given length, and said sections are wound on to the tire
blank.
[0011] The processes for producing undulating plies the
reinforcement cords of which have undulations in the transverse
direction of the plane of the ply are known and are described by
way of example in document EP 724 949. They consist of supplying
the reinforcement cords at a given speed and, using a given means,
displacing the reinforcement cords transversely to the machine
direction so as to create an undulation of the reinforcement cords,
and to deposit these cords on a support which may be a strip or a
ply of rubber or of plastics material. The speed of the support is
adapted to receive the cords.
[0012] It is also possible to deposit a second layer of support
material to ensure that the cords thus sandwiched between two
strips of rubber or plastics material are held properly in
position. The rubber plies also have the function, as will be seen
hereafter, of providing the undulating ply thus obtained with a
certain longitudinal tensile strength so as to permit manipulation
of the ply in the subsequent assembly operations, without adversely
affecting the geometric characteristics of the undulations imparted
to the reinforcement cords.
[0013] The ply of finished product thus obtained may be cut into
one or more sections of given length which can be wound on to a
tire blank in a first diameter. Upon the shaping in the press, the
reinforcement cords are brought to a second diameter, greater than
the previous one, and then lose their undulations and adopt a
substantially rectilinear direction forming an angle equal to zero
degrees with the longitudinal direction.
[0014] This embodiment yields good results, but requires rigorous
control of the depositing of the cords to prevent them becoming
superposed on one another, in particular when there is a large
number of cords to be deposited on strips of great width, which
involves considerable and hence costly dedicated means.
[0015] This is why attempts have been made to find an embodiment
which is more flexible and less demanding in terms of capital
investment, while having available a semi-finished product capable
of being used without deformation on conventional assembly
means.
[0016] The continuous production of straight-cord plies is widely
known. The traditional manufacturing means consist of a set of
calenders for coating a ply of reinforcement cords arranged side by
side, and parallel to one another in the longitudinal direction,
with a rubber mix. The semi-finished product thus formed is in the
form of a continuous strip, commonly known as a straight-cord ply,
in which the reinforcement cords are covered by a controlled
thickness of mix, and in which the spaces between the cords are
filled with said mix. Plies of this type are manufactured
industrially at relatively low cost.
[0017] The problem which the invention solves is to propose a
device and a process which make it possible to produce a continuous
undulating ply from a straight-cord ply produced on a traditional
means.
[0018] The device according to the invention comprises: [0019]
means for delivering, at a given controlled speed V1, a continuous
straight-cord ply composed of a ply of rubber mix reinforced by
cords arranged side by side and parallel to one another in the
longitudinal direction at a given pitch, [0020] means for
displacing the whole of said straight-cord ply in alternating
manner transversely to the machine direction and in the plane of
the ply, [0021] receiving means arranged downstream of the
transverse displacement means and cooperating with the latter,
having a linear speed V2 less than V1, [0022] means for applying
retaining cords arranged on the downstream part of the receiving
means, [0023] means for laying or conditioning the undulating
ply.
[0024] The means for displacing in alternating manner transversely
to the machine direction and in the plane of the ply have the
technical effect of imparting an undulating form to the entire ply
and cords forming it, when said ply is deposited on an axially
fixed receiving means.
[0025] The linear speed in the longitudinal direction of the
receiving means (V2) is adjusted relative to the delivery speed of
the straight-cord ply to the entrance to the device such that the
ratio of the speeds V1/V2 corresponds to the ratio of a length of
undulating cord between two given points and the length of the
chord joining these two points.
[0026] An other process consist in passing the ply between a pair
of gear-shaped roller in meshing engagement to undulate the ply in
a direction perpendicular to the plane of the ply and passing the
shaped ply between a pair of rolls to lay down the undulated ply
into a planar arrangement as described in patent EP 431 187.
[0027] However, even though the semi-finished product thus obtained
does indeed have the required undulating form, it will be observed
that it is unusable as-is on conventional manufacturing means owing
to the total absence of longitudinal tensile strength once detached
from the receiving means. The ply tends to readopt the form of a
straight-cord ply.
[0028] This phenomenon is accentuated further when straight-cord
plies containing metal reinforcement wires are used. The latter,
after having been formed into an undulating shape, act as springs
and develop elastic forces the resultant of which is a longitudinal
force, the effect of which is to detach the ply from the support
and to cause kinking, making it unsuitable for use.
[0029] This problem is solved by depositing rectilinear retaining
cords on at least one of the faces of the undulating ply in the
longitudinal direction. The retaining cords are arranged
transversely at a given pitch greater than the pitch of the
reinforcement cords. Surprisingly, the undulating ply obtained does
not kink and retains its geometry, even in the case of metal
reinforcement wires of great stiffness, subject to adapting the
laying pitch of the retaining cords.
[0030] Thus, by judicious selection of the pitch and the strength
of the retaining cords, it is possible to impart to the
semi-finished product sufficient tensile strength to make it
capable of being satisfactorily used on conventional manufacturing
means, and in particular to make it capable of being subjected to
the longitudinal forces linked to the laying tensions imparted to
the product during the assembly operation.
[0031] A laying pitch for the retaining cords of between 10 and 50
mm makes it possible to fit the majority of configurations tested.
Selecting a lesser pitch is recommended for the metal reinforcement
wires of great stiffness such as mentioned above; a laxer pitch can
be adopted for plies comprising textile reinforcement cords.
[0032] To make this undulating ply usable in a tire, it is also
advisable to ensure that the undulating ply, as defined above, once
integrated into the construction of a tire blank, can undergo the
final shaping such that the reinforcement cords form a
substantially zero angle with the longitudinal direction. To this
end, it is advisable to select the nature of the retaining cord
judiciously.
[0033] A first possibility consists of selecting an elastic
retaining cord. By suitably adapting the laying pitch of the
retaining cords and the elasticity of each of said retaining cords,
an attempt will be made on one hand to stabilise the undulating ply
in the longitudinal direction when the latter is detached from the
receiving means or the conditioning means, and on the other hand to
ensure that, during the shaping, the additional force for
elongating the retaining cords until the reinforcement cords are
aligned with the longitudinal direction is negligible.
Consequently, the elasticity of the retaining cords must be neither
too great nor too low.
[0034] In practice, an undulating fabric having undulations of a
period equal to 115 mm with an amplitude of 8 mm was satisfactorily
produced from a straight-cord ply composed of cabled metal
reinforcement wires of type 2/23 arranged with a density of 143
wires per dm, using elastic retaining cords having an elongation of
approximately 5% at 5 daN at a pitch of 30 mm. The pitch of the
retaining cords was reduced to 25 mm when the metal wire was
replaced by a cabled metal wire of type 19/18.
[0035] A second possibility consists of using a retaining cord
having low elasticity but having a low tensile strength. Under
these conditions during the shaping in the press the retaining
cords break, enabling the reinforcement cords to align themselves
with the longitudinal direction.
[0036] In practice the brittle retaining cords have a tensile
strength of between 2 and 10 daN.
[0037] A device according to the invention is described hereafter
with reference to the appended figures, in which: [0038] FIG. 1 is
a diagrammatic view of a section of undulating ply, [0039] FIG. 2
is a diagrammatic view of a device according to the invention.
[0040] FIG. 1 is a diagrammatic plan view of a section of
undulating ply O in which there can be seen the reinforcement cords
R arranged side by side in the longitudinal direction L at a given
pitch p1, in which the cords form undulations in the transverse
direction T of an amplitude A and of a period P in the plane of the
ply O. The retaining cords B are arranged in rectilinear manner in
the longitudinal direction L on one face of the ply O. They are
spaced apart by a pitch p2 greater than the pitch p1 of the
reinforcement cords.
[0041] FIG. 2 is a diagrammatic perspective view of a device
capable of producing undulating fabrics according to the
invention.
[0042] This device comprises means for delivering a continuous
straight-cord ply D at a controlled speed V1. These means are not
shown in FIG. 2 but are formed of conventional means for feeding
and unwinding a continuous strip of flat product arranged on a
protective backing. The straight-cord ply D is composed of
reinforcement cords arranged side by side and parallel to one
another in the longitudinal direction at a given pitch. The pitch
of the reinforcement cords is substantially equal to the pitch
p1.
[0043] The ply is wound onto a first roller 1, referred to as
undulation roller, which is moved in a transverse alternating
movement in the direction T, parallel to the axis of rotation of
the roller. The speed of rotation of the undulation roller 1 is
adjusted such that its circumferential speed is equal to V1.
[0044] A second roller 3, referred to as receiving roller, is
arranged downstream of the undulation roller. The receiving roller
3 onto which the ply is also wound on emerging from the undulation
roller has its speed of rotation adjusted such that its
circumferential speed V2 is less than V1.
[0045] The distance d between the circumference of the undulation
roller and the circumference of the receiving roller is
adjustable.
[0046] By displacing the undulation roller 1 in alternating manner
in the transverse direction T with a given period and frequency, an
undulation of all the reinforcement cords R of the ply O in the
plane of said ply is created when the latter is deposited on the
receiving roller 3.
[0047] The period and the amplitude of the transverse movement of
the undulation roller 1, the distance d, and the speeds V1 and V2
are adjusted in known manner in order to obtain a period P and an
amplitude A of the undulation of the reinforcement cords R, once
the latter have been deposited on the receiving roller 3.
[0048] It is nevertheless observed, experimentally, that the forces
linked to the thrust of the whole of the ply in the transverse
direction tend to cause said ply to slip on the undulation and
receiving rollers. It is therefore important for the receiving
roller and the undulation roller to be designed to permit high
transverse forces.
[0049] The effect of the slipping in the transverse direction is to
destroy the geometric regularity of the undulations. It can be
overcome by treating the surface of the rollers so as to improve
the adherence of the ply to said rollers.
[0050] To this end, a first solution consists of imparting magnetic
properties to the surface of said rollers. This solution is
obviously viable only in the event that the ply is formed of metal
reinforcement wires.
[0051] Another solution consists of varying the surface temperature
of the rollers.
[0052] It is also possible to adjust the tension between the feed
and unwinding system of the straight-cord ply and the undulation
roller. However, it will be observed that the tension between the
undulation roller and the receiving roller must be adjusted to
values which are as low as possible in order to enable the ply to
be deposited without longitudinal deformation on the receiving
roller.
[0053] The means for applying the retaining cords (2, 4) are formed
of an unreeling means 4 and an application roller 2 which is
arranged on the downstream part of the receiving means. The
retaining cords B are deposited in rectilinear manner on at least
one of the faces of the undulating ply O so as to prevent any
longitudinal deformation of said ply when the latter is detached
from the receiving roller or its conditioning support.
[0054] The conditioning means are formed by a backing 5, travelling
at the speed V2, on which the undulating ply O is deposited. The
undulating ply O and the backing 5 are wound jointly about a
motor-driven shaft 6.
[0055] It is possible to produce equivalent devices using conveyor
belts instead of the rollers; in that case it will be necessary to
ensure that the mobile parts are capable of withstanding the
transverse forces linked to the movements of the ply under the
effect of the undulation.
[0056] It is also possible to conceive of the undulating strip
being deposited on a transfer means linked to the cylindrical
surface of an assembly drum intended for producing a tire or
directly on the surface of an assembly drum. This arrangement makes
it possible to dispense with the conditioning and storage
operation, and may prove of interest when the consumption of
undulating ply at the entry to the assembly machine is high.
[0057] The process for manufacturing an undulating ply (O) from a
straight-cord ply using the device described above comprises the
following steps: [0058] producing a continuous strip of continuous
straight-cord ply (D) composed of a ply of rubber mix reinforced by
reinforcement cords (R) arranged side by side and parallel to one
another in the longitudinal direction (L) at a given pitch (p1),
using a traditional process, [0059] delivering said straight-cord
ply (D) at a controlled linear speed V1, [0060] displacing in
alternating manner the whole of said ply transversely to the
machine direction in the plane of the ply, [0061] applying the
undulating ply (O) thus formed to a receiving means (3) having a
linear speed V2 less than V1, [0062] depositing on at least one of
the faces of the undulating ply (O), in the longitudinal machine
direction, rectilinear retaining cords (B) by arranging them
transversely at a given pitch (p2), [0063] depositing the
undulating ply (O) on a transfer or conditioning means (5, 6).
[0064] These process steps can easily be integrated into the
general process of manufacturing a tire either at a centralised
means which distributes the finished products over the entire tire
assembly means, or directly at an assembly machine owing to its
great simplicity of use and flexibility of use.
[0065] Furthermore, although the use of undulating plies has become
widespread for the production of the crown reinforcement plies of
tires, the process and the device described above can be adapted
perfectly well for the production of undulating plies located in
other parts of the tire.
* * * * *